Sea level sensors spread across Chatham

Mary Landers @MaryLandersSMN

Tuesday

May 14, 2019 at 4:28 PMMay 14, 2019 at 4:47 PM

On a warm evening last month, Georgia Tech Senior Research Scientist Russ Clark climbed atop a Burnside Island house in his quest to collect more data about sea level rise and flooding in Chatham County.

Balancing precariously, he drilled in place the exterior portion of a "gateway" device positioned to collect signals from water level sensors as far as four miles away and relay the data back to him. Moving inside the house, Clark and homeowner Richard Simmons, who volunteered the space, clambered around the attic to install the gateway's brains and connect it to the Internet and a working power outlet.

With the gateway operating, Clark drove down the road to install a new sea level sensor on a bridge over the canal running behind Simmons' house. The devices are shoebox-sized, about $300 each and sturdy, running on ordinary D batteries that should last three to five years. The sensors use ultrasonic pulses to measure the distance to the water, so they avoid many of the problems associated with staying wet. It was the 13th such device the Smart Sea level Sensor Project installed since last summer. Another dozen have since been installed and the project aims to have 50 up and running by the heart of hurricane season.

The goal is to provide emergency managers and area residents with real time measures of rising water at bridges, creeks and backyard docks around the county. It's a need that Hurricanes Matthew and Irma made evident.

"The pitch I made after Matthew and Irma is we have this one tide gauge at Fort Pulaski," Clark said at a session about the project at the Chatham County Hurricane Conference earlier that same day. "It told us one perspective. Just like everyone else, I was hitting reload on my web browser as fast as I could during each of those storms. Still today if you look at graphs from Pulaski it says the peak water level was the same for both storms. Even that Matthew was higher. In reality, most of the county saw more significant flooding from Irma because of the wind and the direction the storm approached. Why do we only have one vantage point, wouldn't it be great to see in real time the impact all over the county?"

The Smart Sea Level Sensors project is marking its first anniversary with a public expo from 3:30 to 6:30 p.m. Thursday at the Jepson Center for the Arts. Their project team and partners will give presentations and hands-on demonstrations, as they give updates on the project. Representatives from project partners, including Savannah, Chatham County, Harambee House, and Georgia Tech, will be in attendance to get feedback from residents to help guide planning for the second year of the project. The showcase will highlight sensor technology, uses of sensor data, and community partnerships.

Simmons, an engineer, volunteered the use of his house and dock for the project, though the dock proved unsuitable because of its roof configuration.

"Data gathering peaks my interest," Simmons said. "We've been out here 11 years so we don't have all the knowledge other people have."

Water comes up onto his property in the highest of high tides. It covered his yard in Matthew and came up even higher in Irma, triggering some new landscaping after the salt water killed some plants. Having the smart sensor nearby will help him and his neighbors keep an eye on their area in the next storm. It's designed to also help emergency managers determine more quickly if the neighborhood is safe to re-enter.

The tide gauge at Fort Pulaski shows sea level rise of about 10 inches over the last 85 years. A similar rise over the next century would be a best case scenario, Clark said. More likely is faster sea level rise, exacerbating an already mounting flood risk. And already Chatham has seen that 65 percent of major flood events in that 85 years have happened since 2015.

"We know that flooding is a fact of life," Clark said. "Even in a minimal (tropical) storm, Chatham County is widely affected. There's very little high ground."

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